Food package construction

ABSTRACT

A construction for a food package consisting of two laminate members. Each laminate member consists of an inner layer, disposed adjacent to the food product, and an outer layer bonded to the inner layer. The inner layers are heat sealed together to enclose the food product in the laminate members. The bonds and tensile strengths of the layers are such that pulling the laminate members apart to open the package results in a delamination of one of the laminate members and the tearing of its inner layer to provide access to the food product.

United States Patent inventor Appl No.

Filed Patented Assignee William Anthony Work Coon Rapids. Minn.

Sept. 4. 1970 Nov. 30, 1971 American Can Company New York, N.Y.

Original application Sept. 25, 1968, Ser. No. 762,501, now Patent No.3,536,501, dated Oct. 27, 1970. Divided and this application Sept. 4,1970, Ser. No. 69,543

FOOD PACKAGE CONSTRUCTION 3 Claims. 5 Drawing Figs.

US. Cl .6 229/87 F, 206/46 F. 229/51 WB int. Cl B65b 25/06 Field ofSearch 229/87 F.

5i WB, 5! ST; 206/46 F; 99/171 LP. 178

[56l References Cited UNITED STATES PATENTS 2,954.116 9/1960 Maso i.229/51 WBX Primary ExaminerD0nald F Norton Atrorneys- Robert P. Auber.George Pv Ziehmer. Ronald A.

Schapira and Leonard R Kohan ABSTRACT: A construction for a food packageconsisting of two laminate members. Each laminate member consists of aninner layer. disposed adjacent to the food product. and an outer layerbonded to the inner layer The inner layers are heat sealed together toenclose the food product in the laminate members, The bonds and tensilestrengths of the layers are such that pulling the laminate members apartto open the package results in a delamination of one of the laminatemembers and the tearing of its inner layer to provide access to the foodproduct.

FOOD PACKAGE CONSTRUCTION CROSS-REFERENCES TO RELATED APPLICATIONS Thisapplication is a division of my copending application, Ser. No. 762,501,now Pat. No. 3,536,501 entitled Food Package and Method of Making Same.

BACKGROUND OF THE INVENTION This invention relates to the packaging offood products and, more particularly, to the packaging of such foodproducts so as to prevent a loss of moisture content therefrom. Theinvention also relates to a package of novel construction which providesfor effective sealing of food products and which is easily opened toprovide for convenient access to the food product.

Heretofore it has been customary to wrap individually sliced foodproducts, such as individual slices of cheese, by wrapping them in aplastic material, such as cellophane. However, it has been observed thatthis material absorbs moisture from the product which results not onlyin a loss of net weight for the slices as packaged but also in an overlydry taste and texture and a deterioration in flavor. Where cheese isconcerned, certain manufacturers have attempted to overcome thesedeleterious efiects by adding an extra amount of cheese to each slice.While this procedure helps to maintain the net weight as posted on thelabel despite the loss of moisture, it is obviously uneconomical anddoes not prevent deterioration of quality caused by the dryness.

Accordingly, it is a primary purpose of the present invention to providean inexpensive, moistureproof package for individually sliced foodproducts wherein the food products are enclosed within a sheet materialsuch as shown in US. Pat. No. 3,285,497. The sheet material comprises alaminate having a first layer of plastic which is capable of being heatsealed to itself and a second layer intimately laminated throughout tothe first layer with the second layer being relatively nonabsorbent andmoisture impermeable to food products. In addition, the second layer hasa higher melting point than the first layer so that heat may be passedthrough the second layers to seal the first layers together. Theindividually sliced food product is wrapped in the flexible wrappingmaterial with the ends of the wrapping material overlapped. The wrappingmaterial is sufficiently wide to provide overhanging lateral portionswhich are fin sealed in conventional manner by the application of heatand pressure. The second layer has a low adhesive affinity for the firstlayer whereby easy access to the package may be had along a line ofseparation beneath the overlapped ends of the wrapping material.

In specific embodiments of the foregoing invention, the first layer ispreferably made from polyethylene and the second layer is preferablymade from polypropylene with the polypropylene layer being from one tothree times as thick as the polyethylene layer. As an optional feature,the terminal portion of the overlapped end of the wrapping material maybe folded under so as to provide means to grasp an end of the packagematerial when it is desired to open the package.

SUMMARY OF THE INVENTION In order to provide a package which provideseffective sealing of food contents and which is easily opened to provideaccess to the food contents, as set forth in the Background of theInvention, this invention, briefly summarized, relates to a packageconstruction wherein the bond between the heat sealed, first layers ofthe laminate sheet material is stronger than the bond between the secondand first layers of the laminate sheet material; wherein the bondbetween the second layer and the first layer of the laminate sheetmaterial is stronger than the tensile strength of the first layer;

and wherein the tensile strength of the second layer is stronger thanthe bond between the first and second layers of the laminate sheetmaterial.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of apackage made in accordance with the present invention;

FIG. 2 is a side elevation view taken in vertical cross section alongline 2-2 of FIG. 1;

FIG. 3 is a fragmentary side elevation view in vertical cross sectionshowing a portion of FIG. 2 drawing to an enlarged scale;

FIG. 4 is a fragmentary side elevation view in vertical cross sectiontaken along line 4-4 of FIG. 1 and drawn to an enlarged scale; and

FIG. 5 is a perspective view of the package of FIG. 1 after it has beenopened.

DESCRIPTION OF THE PREFERRED EMBODIMENT While the various features ofthis invention are hereinafter illustrated and described with respect toa cheese product and more particularly to individual slices of cheese,it is to be understood that the various features of this invention canbe utilized singly or in various combinations thereof with other foodproducts and with food products in forms other than individual slices.Therefore, this invention is not to be limited merely to the embodimentsillustrated in the drawings because the drawings are utilized hereinmerely to illustrate one of a wide variety of uses of this invention.

Referring now to FIGS. 1 and 2 of the drawing, there is illustrated awrapped package, generally designated 10. A food product 12, such as anindividual slice of cheese, is contained within the package 10. Aflexible wrapping material 25 is wrapped completely around the foodproduct 12 beginning at the top thereof and proceeding to envelope theentire slice of cheese.

The wrapping material consists of a first layer of plastic film 14 whichcontacts the top and bottom of the food product 12 and which is capableof being heat sealed to itself. Such a material may be polyethylene, forexample. A second layer of plastic material 16, such as polypropylene,is intimately laminated throughout its surface area to the first layer14 of polyethylene. The second layer of plastic material 16 not onlyprovides the nonabsorbent and moisture impermeable qualities to thewrapping material but also has a low adhesive affinity for the firstlayer of plastic material.

The flexible laminated wrapping material has a width sufficient toprovide overhanging portions on opposed sides of the sliced food product12 whereby the overhanging portions may be fin sealed at 18 and 20. Inaddition, the wrapping material has a length sufficient toprovide anoverlapped portion 22 whereby the overhanging portions of the underlyingend portion 220 and the overlying end portion 22b of the overlapped endportion 22 of the wrapping material may simultaneously be tightly closedbut not sealed at 180 and 20a when the fin seals 18 and 20 are made.This tight closing without sealing allows for easy opening of theoverlapped portion in a manner which will be hereinafter more fullydescribed.

As best shown in FIG. 4, the fin 20 is sealed at the interface betweenthe first layers 14. The second layer 16 has a relatively low adhesiveaffinity for the first layer and thus, the layers 14,16 may be separatedor delaminated from each other at interfaces 16a or 1612.

This delamination at interfaces 16a or 16b provides for easy opening ofthe package. As shown in FIG. 5, the delamination may take place atinterface 16a. The delamination is accompanied by longitudinal tearingof the first layer 14 along lines 27 and 28. It is to be understood thatdelamination may occur at both interfaces 16a and 16b in which event thefirst layer would tear laterally along lines 14c and 14d (FIG. 5) whichwould occur in a random manner.

The package of the present invention includes a wrapping material havingnonabsorbent and moisture impermeable qualities. Moreover, the wrapperis constructed so as to be opened easily.

As an optional feature, the terminal portion of the over lapped portion22 may be provided with a folded under edge 26 so as to facilitate aneasy grasp of the edge of the overlapped portion 22 of the packagingmaterial.

While the invention and many of its attendant advantages will beapparent from the foregoing description, a review of the method stepspracticed in manufacturing the package will effectively summarize thefeatures of this invention. An individual sliced food product, such as aslice of cheese, is wrapped in the flexible wrapping material which hasa sufficient length to provide an overlapped end condition and which issufiiciently wide to provide overhanging lateral por tions. As anoptional step, the terminal end of the overlapped portion may be foldedunder to provide an easy access to the package. The overhanging lateralportions are then fin sealed at 18 and 20 and are tightly closed at 18::and 20a thereby obtaining an efi'ectively sealed food product. Becausethe outer layer 16 has a low adhesive affinity for the inner layer 14,the line of separation 24 beneath the overlapped portion 22 provides aneasy access to the package when the folded under portion 26 is graspedand pulled to the right in FIG. 3.

According to the principles of the present invention, as justexemplified by the package 10 and its sealed fin 20, a construction fora food package is shown in FIGS. 4 and 5 which comprises two laminatemembers A and B and means C for pulling the laminate members apart toopen the construction by delamination and tearing of one of the laminatemembers A,B. Each laminate member A,B consists of the first or innerlayer 14 bonded to the second or outer layer 16. The inner layers 14 areheat sealed together along the confronting peripheral margin portions18,20 of the laminate members A,B to enclose the food product within thelaminate members. The underlying end portion 22a of one laminate member,the overlying end portion 22B of the other laminate member, and theirassociated line of separation 24 constitute means C for pulling thelaminate members apart to open the construction by delamination of oneof the laminate members A,B along the confronting margin portions 18,20.

The process of delamination to open the construction involves pullingthe laminate members A,B apart to initially cause one of the laminatemembers to delaminate in the confronting margin portions 18,20 of theone-laminate member with the other laminate member. The one-laminatemember tends to delaminate because the bond between its inner and outerlayers 14,16 is not as strong as the tensile strength of its outer layer16 or as the heat sealed bond between the inner layers 14 of thelaminate members A,B. As shown in FIG. 5, laminate member A is thelaminate member which delaminates. Thus, opening of the construction ofthe subject invention is initiated by delamination at interface 16a or1612 rather than by tearing of the outer layer 16 or the unbonding oftheinner layers 14.

Delamination is accompanied by longitudinal tearing of the inner layer14 of the one-laminate member along lines 27 and 28. While pulling ofthe laminate members A,B continues, the inner layer 14 tends to tearbecause its tensile strength is less than the tensile strength of thebond between the inner and outer layers 14,16 of the one laminatemember. As shown in H6. 5, the inner layer 14 of laminate member Atears. Thus, opening of the construction of the subject invention isaccompanied by longitudinal tearing of the inner layer 14 of theonelaminate member rather than by continued delamination of theone-laminate member, beyond the confronting margin portions 18,20 of theone-laminate member.

In the manufacture of the wrapping material 25, it is preferred to add aslip-enhancing material to the polypropylene layer 16. This may beaccomplished conveniently by the application of a light starch dust tothe polypropylene layer 16 after it emerges from the conventionalcasting roll while en route to final rewindingi One suitable material isOxy-Dry No. 644 which is an industrial food grade starch marketed byOxy-D S ray Corp. of Chicago, lliinois.

e wrapping materia 5 may be made in various thicknesses. Preferably, thewrapper is L25 mils (0.00125 inches) in total caliper, comprising l.05mils polypropylene and 0.20 mils polyethylene. The polyethylene layermay vary from 0.! to 0.5 mils. The foregoing are preferred ranges ofthickness and other may be selected so to achieve maximum economywithout sacrificing the nonabsorbent, water impermeable and easy openingqualities of the wrapper.

In the process for making the film, the components are extrudedsimultaneously through a slot die extruder. The resins are actuallyunited in the die which has a manifold permitting the components todevelop their respective layers. The percentage of the layers iscontrolled principally by adjustment of manifolds within the die andcontrolling the amount of resin pumped into the die. While it isdesirable to use as much of a percentage of polyethylene as possiblebecause of its lower cost, in all instances to date the film hasconsisted of polypropylene having a thickness from one to six times thethickness of polyethylene.

It is to be understood that the foregoing sheet material constructionmay be a substrate portion of a lamination including layers of othermaterial which have protective properties for packaging food or otherproducts. Such other material may include polyvinylchloride, Saran,Mylar, nylon and the like. Such layer materials may be combined in knownmanners according to the protective properties desired. The sheetmaterial of the present invention would provide protective propertiesand an easy opening feature to such laminations.

It is thought that the invention and many of its attendant advantageswill be understood from the foregoing description, and it will beapparent that various changes may be made in the form, construction andarrangement of the parts without departing from the spirit and scope ofthe invention, the form hereinbefore described being merely a preferredembodiment thereof.

lclaim:

1. In a package, for a product comprising a first laminate member havinga first outer layer, intimately bonded to a first inner layer; a secondlaminate member having a second outer layer, intimately bonded to asecond inner layer; said first and second inner layers being heat sealedtogether along the confronting peripheral margin portions of saidlaminate members to enclose said product within said laminate members;and means for pulling said laminate members apart to open said packageby delamination of said first laminate member, the improvementcomprising:

the bond between said inner layers being stronger than the bond betweensaid first outer layer and said first inner layer;

the bond between said first, outer layer and said first inner layerbeing stronger than the tensile strength of said first inner layer; and

the tensile strength of said first outer layer being stronger than thebond between said first outer layer and said first inner layer so thatas said laminate members are pulled apart, said first outer and saidfirst inner layers will initially unbond in the confronting peripheralmargin portions of said first outer layer with said second outer layerwhere said inner layers are bonded and so that said first inner layerwill tear to open the package as the pulling apart of said laminatemembers continues beyond the unbonding of said first outer and saidfirst inner layers in said confronting peripheral margin portions ofsaid outer layers.

2. The package of claim A wherein said first outer layer and said firstinner layer are coextruded as a laminate web.

3. The package of claim A wherein said first outer layer ispolypropylene; said first inner layer is polyethylene; and said firstouter layer is from one to six times as thick as said first inner layer.

1. In a package, for a product comprising a first laminate member havinga first outer layer, intimately bonded to a first inner layer; a secondlaminate member having a second outer layer, intimately bonded to asecond inner layer; said first and second inner layers being heat sealedtogether along the confronting peripheral margin portions of saidlaminate members to enclose said product within said laminate members;and means for pulling said laminate members apart to open said packageby delamination of said first laminate member, the improvementcomprising: the bond between said inner layers being stronger than thebond between said first outer layer and said first inner layer; the bondbetween said first, outer layer and Said first inner layer beingstronger than the tensile strength of said first inner layer; and thetensile strength of said first outer layer being stronger than the bondbetween said first outer layer and said first inner layer so that assaid laminate members are pulled apart, said first outer and said firstinner layers will initially unbond in the confronting peripheral marginportions of said first outer layer with said second outer layer wheresaid inner layers are bonded and so that said first inner layer willtear to open the package as the pulling apart of said laminate memberscontinues beyond the unbonding of said first outer and said first innerlayers in said confronting peripheral margin portions of said outerlayers.
 2. The package of claim A wherein said first outer layer andsaid first inner layer are coextruded as a laminate web.
 3. The packageof claim A wherein said first outer layer is polypropylene; said firstinner layer is polyethylene; and said first outer layer is from one tosix times as thick as said first inner layer.